The topic of primary interest is the remarkably slow and variable responses which are characteristic of the behavior of young children. Our major objective is to discover some of the physiological factors relating to the slow responses of children and to the changes in response speed which take place during growth and development. The research focuses on the investigaton of brain electrical activity. Cerebral recovery functions to peripheral (auditory) stimulation, and the spontaneous activity of the electroencephalogram (EEG) will be investigated. A conceptual framework is proposed in which speed of response processing is thought to be determined by an interaction of a cortical timing or gating cycle and the cortical excitability cycle. In the context of this model, consecutive half waves in the spontaneously- occurring EEG are manifestations of the cortical timing cycle. Properties of the cortical timing cycle will be studied by casting measurements of the durations of EEG half waves into an interval histogram, and using the first four central moments to characterize the distribution. Cerebral recovery functions will be used to study the time characteristics of the cortical excitability cycle. Another objective is to determine whether central moments of EEG interval histograms can be used to chart the course of normal brain development. Finally, we will determine whether children with learning disorders have EEG interval histograms which show evidences of delayed development.